Controllable pitch propeller



July 18, 1944. c; UNTERBERG 2,353,773

CONTROLLABLE PITCH PROPELLER Filed Feb. 20, 1945 7 Avvtnvrol? i 67142455(/A/TE 5/?6 0 ill/f Patented July 18, 1944 conraomnnrrronrnorntwaf v:CharlesUnterbex-g, Mobile, Ala. Application February 20,1913, seuuvdmssa mins; (or. 110-103) 3 (artist was... ta of March a, 1883, asamended 1 928: 370 0. G. 757) The invention described herein may bemanufactured and used by or for Government for governmental purposes,without the payment to me of any royalty thereon.

This invention relates generally to variable pitch propellers and moreparticularly to aircraft propellers.

An object of the invention is to provide a propeller of this kind whichis of simple construction and of few parts, economically made and'easily assembled and disassembled.

Another object is'to provide a propeller the pitch of which may behydraulically controlled without the necessity of providing rotatingpipe Joints to convey the hydraulic fluid from a nonrotating source tothe blade operating means.

Another object is to provide a propeller of this type which may be usedon warcraft for firing through the propeller shaft. 7

Another object is to provide a variable pitch propeller in which thepitch changing mechanism may be constructed as a unit and be removablewithout disturbing the main propeller hub on its shaft.

Otherobjects and meritorious features will be noted as the invention ismore particularly de- 42 and inner seal rings 44 being carried in thepiston. A series of circumferentialiy spaced piston rods 43 extendrearwardly" from the piston scribed with reference to the drawing,wherein,

Fig. 1 is a plan view of the complete propeller.

Fig. 2 is a transverse section taken at 2-2 of Fig. 1 showing thepropeller with the hydraulic control unit removed.

Fig. 3 is an axial section taken at 3-3 of Fig. 4 through the hydrauliccontrol unit.

Fig. 4 is an end view of the entire unit taken from the line 4-4 of Fig.3.

Referring now to the drawing, a propeller hub ID has radially extendingbosses l2 for holding the anti-friction bearings l4 which rotatablysupport the shanks l6 of the propeller blades l8. The hub I0 issplinedly mounted on the crank shaft (not shown) which extends from thenose of an aircraft engine 20 or it may be secured to a propeller shaft22 which may be gear driven oil the engine shaft, a nut 24 is providedon the end of the propeller shaft to hold the hub in place. An opening26 is provided whereby a machine gun may be fired through the shaft. Onthe forward face of the huh I 0 are mounting pads 28 with tappedopenings for securing the control unit to the hub.

The control unit comprises a closed container 30 made up of an outercylinder 32 and an inner cylinder 34 joined by a front head 36 and aback head 38, the inner cylinder extending rearwardly 5 *racks are sopositioned that through the back head. The parts 32, 34, 36 and 33 areshown integral although they may preferably. be made separately andappropriately Joined together.

An annular piston 40 is slidably fitted both to the inside of the outercylinder 32 and to the outside of the inner cylinder 34, outer sealrings through'stufllng boxes 43 in the rear head 33 and carry racks 50at their rearward ends. The they engage gears 52 which are attached tothe blade shank 13, whereby axial movement of the piston 40 rotates theblades l8.

Pumps 54, each driven by a reversible electric motor 58, are mounted onthe outside of the rear head". Pipes 53 and respectively connect thepumps to the compartments 64 and 62 into which the piston 40 divides thecontainer 30, pipe 58 being the suction and pipe 60 the discharge whenthe pumps rotate one direction and vice versa when the pumps are rotatedOpposltely. Filler plugs 63 are provided for use in supplying hydraulicfluid to the several compartments. The front of the control unit isprovided with a cap 68 which is held on by screws I0. At the rear endthe protruding end of the inner cylinder is reinforced by ribs 12 whichwiden out to form pads as at 14 to match the pads 28 on the propellerhub through which the bolts 18 extend for attaching the control unit tothe propeller hub. v

Slip rings '18 are insulatedly supported on the rear face 01' thepropeller hub III for bringing the electric current to the severalmotors 56, while brushes insuiatedly carried on the nose of the engine20 feed current to the rings. The switch for rotating the motors in oneor the other direction for pitch increase or decrease is not shown sinceit forms no part of the present invention but it may be manual orautomatic or a combination of both, as already well known in the priorart.

In substantially all known variable pitch propiston rods 46, tomechanically arrest movement of-the piston when the desired limit isreached,

provided the pumps 54 are equipped with a relief valve to permitcontinued rotation without ininner ends of the pumps 54 are rotated onedirection they will pump out of the chamber 62 and into the chamber 4whereby the piston 40 is moved forwardly and the racks 50 rotate theblades in the directlon of the arrow 82. Opposite rotation of'the pumpswill, of course, rotate the blades oppositely.

Having shown and described an embodiment of my invention whereby theobjects set forth are attained, I claim:

, 1. A variable pitch propeller-comprising a propeller hub, radiallyextending bosses on said hub.

blades having shanks rotatable in said bosses,

and gears on the inner ends ofsaid shanks, in

combination with a self contained bodily remov- I able control unit.concentrically secured to the forward end of saidhub and comprising afluid container made up oi an outer'cylinder, a concentric innercyllndeaand two heads for closing the ends of the annular space betweensaid cylinders, an annuiar piston in said container dividing the annularspace into two compartments, piston rod: extending from said pistonthrough the rearward head and into said hub, racks on the free ends ofsaid rods positioned to mesh with said gears, and an electricallyoperated reversible pump carried on and bodily removable with thecontrol unit, arranged for selectively pumping out of either compartmentinto the other.

2. A variable pitch propeller comprising a propeller hub, radiallyextending bosses on said hub, propeller blade shanks rotatable in saidbosses, and gears on the inner ends of said shanks, in combination witha self contained bodily removable control unit, concentrically securedto the front of said hub to rotate therewith and comprising a fluidcontainer made up of an outer cylinder, an inner cylinder concentricwith the outer cylinder, and two cylinder heads for closing the ends ofthe annular space between said cylinders, an annular piston in saidcontainer dividing the annular space into two com- V partments,circumferentially spaced apart piston rods carried by said piston andextending rearwardly through the rear piston head and into said hub,rackson the free ends of said rods positioned to mesh with said gears,and reversible electric motor driven pumping means, carried on the rearpiston head and removable bodily with said unit and adapted to berotated in one direction for pumping out of the front compartment intothe rear compartment, and in the other direction for pumping out of therear compartment irtothe front compartment.

' CHARLES 'UN'IERBERG.

